Investigations of Particle Evaporation Kinetics Using Ultra-High Purity Aerosolization and Heating

DEREK OBERREIT, Jikku Thomas, Michael Walker, Kanomax FMT, Inc.

     Abstract Number: 408
     Working Group: Instrumentation and Methods

Abstract
Particle precursors in semiconductor process chemical have received increasing attention due to their ability to form a defect-causing particle through precipitation from droplets remaining on the wafer surface following liquid contact. This particle formation mechanism is mimicked using aerosolization of the liquid and subsequent analysis by common aerosol measurements. While this can provide insight into the propensity of dissolved contaminants in a process chemical to form defect-causing particles, it does not provide much insight into the ability to mitigate them using thermal techniques. In this work, we present a method for qualitatively determining the evaporation kinetics of the particle precursor material using high purity, nano-droplet aerosolization with a compact aerosol sample heater.

To demonstrate the capability of this system, we utilized tandem aerosolization - electrical mobility sizing using ultrapure water doped with varying concentrations of high molecular weight organics often found in ultrapure water. When the aerosol is heated, the semi-volatile components evaporate, which shifts the mode of the aerosolized particle distribution to smaller sizes. The kinetics of the particle evaporation is then probed by varying the aerosol flow rate through the heater at several precursor concentrations and heater temperatures.

The results of this study are expected to yield qualitative thermal decomposition profiles and rates, serving as guideposts for the effectiveness of thermal mitigation.